Method for determining proximity relative to a critical structure

ABSTRACT

A system for determining proximity of a surgical device relative to an anatomical structure includes at least one surgical device having a sensor assembly operably coupled to a processing unit and configured to transmit at least one electrical signal generated by the processing unit through a target anatomical structure to elicit a measurable response from the target anatomical structure. The processing unit is configured to calculate a signature property value of the target anatomical structure based on the measurable response. The processing unit is configured to identify the target anatomical structure based on a comparison between the signature property value and at least one other signature property.

BACKGROUND

1. Technical Field

The present disclosure relates to open or endoscopic surgicalinstruments and methods for treating tissue. More particularly, thepresent disclosure relates to a system and method for determiningproximity of a surgical device relative to critical anatomicalstructures utilizing signature properties values of such structures.

2. Background of Related Art

A hemostat or forceps is a simple plier-like tool that uses mechanicalaction between its jaws to constrict vessels and is commonly used inopen surgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue.

Over the last several decades, more and more surgeons are complementingtraditional open methods of gaining access to vital organs and bodycavities with endoscopes and endoscopic instruments that access organsthrough small puncture-like incisions. Endoscopic instruments areinserted into the patient through a cannula, or port, that has been madewith a trocar. Typical sizes for cannulas range from three millimetersto twelve millimeters. Smaller cannulas are usually preferred, which, ascan be appreciated, ultimately presents a design challenge to instrumentmanufacturers who must find ways to make surgical instruments that fitthrough the cannulas.

As mentioned above, by utilizing an electrosurgical instrument, asurgeon can either cauterize, coagulate/desiccate and/or simply reduceor slow bleeding, by controlling the intensity, frequency and durationof the electrosurgical energy applied through the jaw members to thetissue. The electrode of each jaw member is charged to a differentelectric potential such that when the jaw members grasp tissue,electrical energy can be selectively transferred through the tissue.

Bipolar electrosurgical instruments are known in the art, as are otherelectrosurgical instruments. Commonly-owned U.S. Patent ApplicationPublication No. 2007-0062017, discloses a bipolar electrosurgicalinstrument. Conventional bipolar electrosurgical instruments may includea cutting blade, fluid applicator, stapling mechanism or other likefeature, in various combinations.

Different types of anatomical structures, i.e. vessels, ducts, organs,may require different energy delivery configurations to effect propertreatment. While a specific energy delivery configuration may beadequate for treating an artery or vein, the same energy deliveryconfiguration may not be suitable for treating a duct. Although incertain scenarios the identity of an anatomical structure being treatedis either known or visually apparent, there may be instances where asurgeon is unable to visually determine the anatomical structure beingtreated. Treating non-target structures with an energy configurationconfigured for a target type structure may cause damage to thenon-target structure and/or result in failure to effect propertreatment.

During certain procedures, surgeons must identify critical anatomicalstructures such as large vasculature or urinary or bile ducts. Thesestructures typically need to be avoided or ligated during a procedure,thus requiring a high degree of confidence when identifying suchstructures.

One complication during laparoscopic procedures in particular, isinadvertently injuring nearby critical anatomical structures due toquick or abrupt movement of instruments within the surgical site, poorvisibility, lack of tactile response, confusion of the anatomy frompatient to patient, or inadequate control of the instrumentation beingutilized to perform the procedure. For example, when performing alaparoscopic cholecystectomy to remove the gallbladder, a criticalaspect of the procedure is the identification of the common bile duct.Injuries to the common bile duct may result in significant health risks.For example, despite the use of increased dissection and cholangiogramsto identify critical structures such as the common bile duct, a commonbile duct injury rate of 0.5% to 1.4% has been reported.

Traditional methods for identifying anatomical structures within thebody are based on sensing physical characteristics or physiologicalattributes of body tissue, and then distinguishing normal from abnormalstates from changes in the characteristic or attribute. For exampleX-ray techniques measure tissue physical density, ultrasound measuresacoustic density, and thermal sensing techniques measures differences intissue heat.

Signature properties of anatomical structures such as electricalconductivity, impedance, thermal conductivity, permittivity, andcapacitance may be measured and compared to known data to distinguishanatomical structures from other anatomical structures and/or knowndata. If these signature properties can be properly elicited from atarget anatomical structure, measureable values that correspond to theseelicited properties may be calculated and compared to known values forpurposes of identifying the target anatomical structure.

SUMMARY

According to an embodiment of the present disclosure, a system fordetermining proximity of a surgical device relative to an anatomicalstructure includes at least one surgical device having a sensor assemblyoperably coupled to a processing unit. The sensor assembly is configuredto transmit at least one electrical signal generated by the processingunit through a target anatomical structure to elicit a measurableresponse from the target anatomical structure. The processing unit isconfigured to calculate a signature property value of the targetanatomical structure based on the measurable response. The processingunit is configured to determine proximity of the at least one surgicaldevice relative to the target anatomical structure based on a comparisonbetween the signature property value and at least one other signatureproperty.

According to another embodiment of the present disclosure, a method fordetermining proximity of a surgical device relative to an anatomicalstructure includes the steps of placing at least one surgical devicehaving a sensor assembly disposed thereon relative to a targetanatomical structure and transmitting at least one electrical signalfrom the sensor assembly through the target anatomical structure toelicit a measurable response from the anatomical structure. The methodalso includes the steps of calculating one or more signature propertiesof the target anatomical structure based on the measureable response andcomparing values of the one or more measured signature properties to atleast one other measured signature property. The method also includesthe step of determining proximity of the at least one surgical devicerelative to the target anatomical structure based on the comparisonbetween the one or more measured signature properties and at least oneother measured signature property.

According to another embodiment of the present disclosure, a method foridentifying an anatomical structure includes the steps of placing atleast one surgical device having a sensor assembly disposed thereonrelative to a target anatomical structure and transmitting at least oneelectrical signal from the sensor assembly through the target anatomicalstructure to elicit a measurable response from the anatomical structure.The method also includes the steps of calculating one or more signatureproperties of the target anatomical structure based on the measureableresponse and comparing values of the one or more measured signatureproperties to at least one other measured signature property. The methodalso includes the steps of identifying the target anatomical structurebased on the comparison between the one or more measured signatureproperties and at least one other measured signature property andselectively applying energy to the target anatomical structure based onthe identifying step.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1A is a schematic block diagram of a monopolar electrosurgicalsystem in accordance with an embodiment of the present disclosure;

FIG. 1B is a schematic block diagram of a bipolar electrosurgical systemin accordance with an embodiment of the present disclosure;

FIG. 2 is a schematic block diagram of a generator in accordance with anembodiment of the present disclosure;

FIG. 3 is a perspective view of a bipolar forceps disposed relative to agallbladder region of a patient in accordance with an embodiment of thepresent disclosure;

FIG. 4A is a perspective view of a bipolar forceps, a grasper, and adissector or probe disposed relative to a gallbladder region of apatient in accordance with another embodiment of the present disclosure;

FIG. 4B is a perspective view of a of a bipolar forceps, a grasper, anda dissector or probe disposed relative to a gallbladder region of apatient in accordance with another embodiment of the present disclosure;

FIG. 5 is a perspective view of probe-type devices and a catheter-typedevice disposed relative to a bladder and kidney region of a patient inaccordance with another embodiment of the present disclosure; and

FIG. 6 is a perspective view of a bipolar forceps disposed relative to agallbladder region of a patient in accordance with an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings. In thefollowing description, well-known functions or constructions are notdescribed in detail to avoid obscuring the present disclosure inunnecessary detail.

An electrosurgical generator according to the present disclosure canperform monopolar and bipolar electrosurgical procedures, includinganatomical tissue ligation procedures. The generator may include aplurality of outputs for interfacing with various bipolar and monopolarelectrosurgical instruments (e.g., laparoscopic electrodes, returnelectrodes, electrosurgical forceps, footswitches, etc.). Further, thegenerator includes electronic circuitry configured to generateelectrosurgical energy (e.g., RF, microwave, etc.) specifically suitedfor various electrosurgical modes (e.g., cut, coagulate (fulgurate),desiccate, etc.) and procedures (e.g., ablation, vessel sealing, etc.).

The present disclosure generally relates to a system for identifying atarget anatomical structure such as, for example, a duct, organ,vasculature, vessel, and the like. The system transmits one or moreelectrical signals from a sensor assembly disposed on one or moresurgical instruments through the target structure to elicit ameasureable response therefrom. Based on the response, the systemcalculates one or more signature property values of the target structureand compares these values to known signature property values of variousstructures and/or to other target structures from which a measurableresponse has been elicited. Based on the comparison, the systemidentifies the target anatomical structure and alerts a user of thesystem as to the distance of the target structure relative to the sensorassembly and/or the identity of the target structure (e.g., duct vs.large artery or background connective tissue).

FIG. 1A is a schematic illustration of a monopolar electrosurgicalsystem 1 according to one embodiment of the present disclosure. Thesystem 1 includes an electrosurgical instrument 2 having one or moreelectrodes for treating tissue of a patient P. The instrument 2 is amonopolar type instrument (e.g., electrosurgical cutting probe, ablationelectrode(s), etc.) including one or more active electrodes.Electrosurgical energy is supplied to the instrument 2 by a generator 20via a supply line 4 that is connected to an active terminal 30 (FIG. 2)of the generator 20, allowing the instrument 2 to coagulate, seal, cut,ablate, and/or otherwise treat tissue. The electrosurgical energy isreturned to the generator 20 through a return electrode 6 via a returnline 8 at a return terminal 32 (FIG. 2) of the generator 20.

Turning now to FIG. 1B, an instrument generally identified as bipolarforceps 10 is for use with various surgical procedures and includes ahousing 15, a handle assembly 30, a rotating assembly 80, a triggerassembly 70, and an end effector assembly 100 that mutually cooperate tograsp, seal, and divide tubular vessels and vascular tissues. Forceps 10includes a shaft 12 that has a distal end 16 dimensioned to mechanicallyengage the end effector assembly 100 and a proximal end 14 thatmechanically engages the housing 15. The end effector assembly 100includes opposing jaw members 110 and 120 that cooperate to effectivelygrasp tissue for sealing purposes. With this purpose in mind, jawmembers 110 and 120 include active electrodes 112 and 122 disposedthereon in a bipolar configuration. Active electrodes 112, 122 areoperably coupled to generator 20 and are configured to selectively applyelectrosurgical energy supplied from the generator 20 to tissue graspedbetween the jaw members 110, 120. The end effector assembly 100 may bedesigned as a unilateral assembly, e.g., jaw member 120 is fixedrelative to the shaft 12 and jaw member 110 pivots relative to jawmember 120 to grasp tissue, or as a bilateral assembly, e.g., jawmembers 110 and 120 pivot relative to each other to grasp tissue.

Examples of forceps are shown and described in commonly-owned U.S.application Ser. No. 10/369,894 entitled “VESSEL SEALER AND DIVIDER ANDMETHOD MANUFACTURING SAME” and commonly-owned U.S. application Ser. No.10/460,926 (now U.S. Pat. No. 7,156,846) entitled “VESSEL SEALER ANDDIVIDER FOR USE WITH SMALL TROCARS AND CANNULAS”.

Although the following disclosure focuses predominately on discussion ofelectrosurgical instruments for use in connection with endoscopicsurgical procedures, open type instruments are also contemplated for usein connection with traditional open surgical procedures. Additionallyand as discussed in greater detail below, the aspects of the presentdisclosure may be incorporated into any suitable electrosurgicalinstrument (e.g., instrument 2, forceps 10) or any suitablenon-electrosurgical instrument (e.g., probes, graspers, prods, clamps,grips, forceps, pliers, cutters, electrocautery devices, etc.).

FIG. 2 shows a schematic block diagram of the generator 20 having acontroller 24, a high voltage DC power supply 27 (“HVPS”), a sensormodule 23, and an energy output stage 28 configured to outputelectrosurgical energy (e.g., microwave, RF, etc.) from generator 20.The HVPS 27 is connected to a conventional AC source (e.g., electricalwall outlet) and provides high voltage DC power to the energy outputstage 28, which then converts high voltage DC power into electrosurgicalenergy for delivery to the active electrode(s) of an electrosurgicalinstrument (e.g., instrument 2, forceps 10, etc.) via the activeterminal 30. In certain embodiments (FIGS. 1A and 1B), theelectrosurgical energy is returned to the generator 20 via the returnterminal 32.

The generator 20 may include a plurality of connectors to accommodatevarious types of electrosurgical instruments (e.g., instrument 2,electrosurgical forceps 10, etc.). Further, the generator 20 may operatein monopolar or bipolar modes by including a switching mechanism (e.g.,relays) to switch the supply of electrosurgical energy between theconnectors, such that, for instance, when the monopolar type instrument2 is connected to the generator 20, only the monopolar plug receiveselectrosurgical energy.

The controller 24 includes a processing unit 25 operably connected to amemory 26, which may be volatile type memory (e.g., RAM) and/ornon-volatile type memory (e.g., flash media, disk media, etc.). Theprocessing unit 25 may be any logic processor or analog circuitry (e.g.,microprocessor, control circuit, etc.) adapted to perform thecalculations discussed in the present disclosure. The processing unit 25includes an output port that is operably connected to the HVPS 27 and/orthe energy output stage 28 allowing the processing unit 25 to controlthe output of the generator 20 according to either open and/or closedcontrol loop schemes.

A closed loop control scheme generally includes a feedback control loopwherein the sensor module 23 provides feedback to the controller 24(e.g., information obtained from one or more sensing mechanisms thatsense various tissue parameters such as tissue impedance, tissuetemperature, tissue conductivity, tissue permittivity, output currentand/or voltage, etc.). The controller 24 then signals the power supply27, which then adjusts the DC power supplied to the RF output stage 28,accordingly. The controller 24 also receives input signals from theinput controls of the generator 20 and/or instrument 2 or forceps 10.The controller 24 utilizes the input signals to adjust the power outputof the generator 20 and/or instructs the generator 20 to perform othercontrol functions. In some embodiments, the generator 20 may utilizeaudio-based and/or a video-based display to inform the user of thesensed tissue parameters in the field of view of the one or more sensingmechanisms.

The processing unit 25 is capable of executing software instructions forprocessing data received by the sensor module 23, and for outputtingcontrol signals to the generator 20 or other suitable operating roomdevices (e.g., camera monitor, video display, audio output, etc.),accordingly. The software instructions, which are executable by thecontroller 24, are stored in the memory 26 of the controller 24. Thecontroller 24 may include analog and/or logic circuitry for processingthe sensed values and determining the control signals that are sent tothe generator 20, rather than, or in combination with, the processingunit 25.

In some embodiments, generator 20 and processing unit 25 may be separatestand-alone units operably connected to each other (not shown) orprocessing unit 25 may be incorporated within generator 20, as shown inFIG. 2. In some embodiments, processing unit 25 may be incorporatedwithin the surgical device being used during a procedure (e.g.,instrument 2, forceps 10). In this scenario, the signal-to-noise ratioof signals transmitted to and from processing unit 25 may be improvedsince the signals may experience a decrease in losses caused by travelthrough relatively long lengths of cable. For ease of disclosure,generator 20 is described as incorporating processing unit 25 andprocessing unit 25 is, in turn, described as being incorporated withingenerator 20.

Processing unit 25 is operably connected to an electrode or sensorassembly 50 (FIG. 3). As will be discussed in further detail below,sensor assembly 50 includes one or more transmitting electrodes 50 a andone or more receiving electrodes 50 b and may be mounted on one or moresuitable electrosurgical instruments such as, for example, monopolarinstrument 2 or forceps 10, or on one or more suitablenon-electrosurgical instruments such as, for example, a grasper 200 or adissector or probe 200′, as shown in FIGS. 4A and 4B, and probe-typeinstruments 300 and 300′ and a catheter 300″, as shown in FIG. 5. Inthis scenario, the generator 20 may include a plurality of connectors toaccommodate non-electrosurgical instruments such that a sensor assembly50 mounted to such an instrument may communicate with the generatorand/or the processing unit 25 for purposes of identifying targetanatomical structures.

Sensor assembly 50 is configured to sense and/or measure variousproperties of anatomical structures and/or tissue such as, withoutlimitation, electrical conductivity, thermal conductivity, fluid flow,temperature, capacitance, permittivity, voltage, current, optical-basedinformation, etc. With these purposes in mind, sensor assembly 50 may beembodied as an impedance sensor, a temperature sensor, an opticalsensor, a fluid flow sensor, a capacitance sensor, a permittivitysensor, a voltage sensor, a current sensor, a pressure sensor, or acombination of any two or more thereof.

In some embodiments, sensor assembly 50 may be mounted on a distal endof one or more electrosurgical and/or non-electrosurgical instrumentssuch that the sensor assembly 50 may be used to sense ahead to the areathat the user is moving the treatment device (e.g., instrument 2,forceps 10) to prevent incidental contact between surgical instrumentsand critical anatomical structures, as discussed hereinabove. In thisembodiment, one or more receiving electrodes 50 b may be disposed on theinstrument the user is moving toward a desired tissue site and one ormore transmitting electrodes 50 a may be disposed on a second instrumentplaced relative to the desired tissue site (e.g., during a dissectionprocedure).

In some embodiments, sensor assembly 50 may be disposed on or splitbetween two separate instruments such that either the transmittingelectrode 50 a or the receiving electrode 50 b is disposed on a firstinstrument and the other electrode 50 a, 50 b is disposed on a secondinstrument. This scenario is shown by way of example in FIG. 5. Forexample, FIG. 5 shows catheter 300″ disposed through a bladder andpartially into the right ureter of a patient and probe 300′ in theproximity of the exterior of said right ureter. One of catheter 300″ andprobe 300′ includes a transmitting electrode 50 a disposed thereon andthe other instrument includes a receiving electrode 50 b disposedthereon to operate in cooperation with the transmitting electrode 50 a.As indicated by arrows “A′” and “B′” in FIG. 5, transmitting electrode50 a may transmit electrical signals directionally or radially outwardfrom within an anatomical structure (e.g., catheter 300″) or toward ananatomical structure (e.g., instrument 300′), such that the transmittedelectrical signals will solicit a response from the target anatomicalstructure that may be processed by the processing unit 25. In thismanner, the processing unit 25 may determine the identity of the targetanatomical structure, as discussed hereinabove.

In certain embodiments, the transmitting electrode 50 a and thereceiving electrode 50 b may be substituted by the active electrodes(e.g., 112, 122) of an electrosurgical instrument utilized in theprocedure such as forceps 10, shown by way of example in FIG. 3. Eitherof electrodes 112, 122 may be the transmitting electrode 50 a and theother electrode 112, 122 may be the receiving electrode 50 b. In thismanner, active electrodes 112, 122 may be utilized to sense tissue ofthe target critical structure so that the user may identify the targetcritical structure prior to the application of treatment energy theretoand avoid inadvertent treatment to surrounding critical anatomicalstructures. In one embodiment, each of the active electrodes 112, 122may be split into more than one active electrode. This configurationallows smaller predefined surface areas that are configured to sourceand/or receive the electrical signal through tissue and, thus, may bemore suitable in larger jaw instruments. Additionally or alternatively,an insulative material (not shown) may be disposed between the jawmembers 110, 120 to limit the surface area of the active electrodes 112,122. In a grasping or bipolar type embodiment, the pressure applied totissue grasped between the jaw members 110, 120 may be optimized toprovide the most accurate information or tissue property data. Forexample, if clamped too hard on a duct, the contents within the duct mayhave limited contribution to the electrical signature of the duct (e.g.,conductivity) or no contribution to the electrical signature of theduct. If the pressure is too light or not controlled, the electricalsignature measurements of the duct may be less repeatable or lessaccurate.

Although the following discussion will relate to a two-electrode methodof measuring signature properties of anatomical structures, othermethods of measuring signature properties of anatomical structures havebeen contemplated by the present disclosure. In the two-electrodemethod, two electrodes are placed in contact with, penetrate into, orare placed in proximity with the tissue and/or the anatomical structureto be tested. In one procedure utilizing the two-electrode method, asinusoidal voltage is applied through an anatomical structure across twoelectrodes and the resultant sinusoidal current flow through thestructure is measured. The magnitude of the structure impedance may bedetermined as the ratio of the root-mean-square (RMS) voltage and thecurrent values. The phase angle of the impedance may be determined asthe delay in radians of the peak sinusoidal current with respect to thepeak sinusoidal voltage. By comparing the resulting impedance valueswith known values for various anatomical structures, the anatomicalstructure may be identified. Embodiments of the present disclosure arenot limited to the methods of determining the signature propertiesdisclosed herein. Any suitable method for measuring signature propertiesof anatomical structures, whether electrical, thermal, optical, or thelike, may be incorporated into the embodiments of the presentdisclosure.

Briefly, a predetermined energy signal is periodically produced by theprocessing unit 20 and applied to the target anatomical structure (e.g.,vasculature, duct, vessel, organ, etc.) through the transmittingelectrode 50 a, 112 and received by the receiving electrode 50 b, 122.The resultant response of the target structure to the electrical signalis processed by the processing unit 25 and is then measured andconverted into a value of a particular signature property by which ananatomical structure may be identified. For example, and withoutlimitation, electrical conductivity, thermal conductivity, hydraulicconductivity, impedance, capacitance, and permittivity are all signatureproperties by which an anatomical structure may be identified. Thesesignature properties as measured may include or capture the contents(e.g., fluids) of the anatomical structure. That is, anatomicalstructures such as vessels or ducts may include fluid content flowingtherethrough such as bile, blood, urine, saliva, mucus, water, feces,digestive enzymes, and the like, that directly affect the responseelicited from the target anatomical structure and, thus, the resultingcalculated signature properties. By capturing the content of ananatomical structure in the signature property measurement, suchanatomical structures may better be distinguished from surrounding orbackground tissue as well as surrounding or attached anatomicalstructures. By comparing such signature property measurements with knownsignature property measurements of various anatomical structures,processing unit 25 may determine, in real-time, the identity of ananatomical structure being sensed by the sensor assembly 50 based on thecomparison between sensed and known signature property measurements.

In other embodiments, assessments of anatomical structure identificationmay be made based on the differences between signature properties ofmore than one anatomical structure being sensed by the sensor assembly50. In this scenario, shown by way of example in FIGS. 4A and 4B, morethan one instrument (e.g., forceps 10, grasper 200, instrument 2,dissector/probe 200′) may be used during a procedure, each of whichincludes a sensor assembly 50 configured to elicit a response from atarget anatomical structure such that the processing unit 25 maycalculate a signature property of such target structure. Based on thedifferences between the calculated signature properties of the differentanatomical structures (e.g., cystic duct vs. cystic artery), asdetermined by the processing unit 25, the user is alerted by theprocessing unit 25 and/or generator 20 as to the identity of such targetstructures. The user may manually make an assessment based on datapresented by the processing device 25 and/or may automatically bealerted as to the identity of sensed anatomical structures, e.g., via avisual display or user interface disposed on the generator 20 and/orprocessing unit 25. Alternatively or additionally, sensor assembly 50may be configured to optically sense the target anatomical structuresuch that the user is able to view the target structure (e.g., via thedisplay on the generator 20).

In some embodiments, sensor assembly 50 may be configured to sensesignature thermal properties of a target anatomical structure. In thisscenario, a contrast agent or fluid having a different temperature thanthe body of the patient such as, for example without limitation, coldsaline or Iodine, may be injected into the body of a patient to betterdistinguish target anatomical structures, for example, by affecting thethermal conductivity of a target anatomical structure. For example, coldsaline flowing through the ureter of a patient will operate todistinguish the ureter from surrounding connective tissues.

In certain scenarios, it may be necessary to differentiate anatomicalstructures utilizing more than one modality and/or more than onesignature property of such structures. For example, the signatureelectrical properties of veins may be similar to that of arteries,thereby making differentiating such structures from each other difficultutilizing only signature electrical properties. Through use of thevarious embodiments of the present disclosure, electrical and/or othersignature tissue properties (e.g., thermal properties) may be sensed andused in combination with other sensed properties such as, for example,pressure within the vein or artery and/or optical data of the vein orartery, to more easily differentiate one from the other.

In operation of one embodiment of the present disclosure, sensorassembly 50 is placed in contact with or in proximity to the targetanatomical structure to be identified. Processing unit 25 produces anelectric signal that is directed into the target structure throughtransmitting electrode 50 a. Processing unit 25 may be configured tocontinuously or periodically produce a signal, or instead the instrumentbeing utilized (e.g., bipolar forceps 10) may include a button or lever124 mounted on housing 15 and/or generator 20 (FIG. 1B) for activatingprocessing unit 25. As discussed above, depending on the application,the electric signal may be of a specific frequency or range offrequencies and of any configuration. The respective portion of thetarget structure disposed between transmitting electrode 50 a andreceiving electrode 50 b (e.g., tissue and fluid contents within thestructure) functions to complete a circuit path therebetween. In thismanner, conductive anatomical structures and/or their conductive content(e.g., bile, urine, etc.) may be utilized to transmit the electricsignal a longer distance between the transmitting and receivingelectrodes 50 a and 50 b such that transmitting and receiving electrodes50 a and 50 b need not be in close proximity to each other to complete acircuit therebetween. These portions of the target structure producecharacteristic responses based on the signals delivered to electrode 50a by processing unit 25. The resulting response is acquired by receivingelectrode 50 b. Based on the response, the processing unit 25 calculatessignature property values of the target structure. By comparing thesignature property values of the target structure with signatureproperty values of other target structures and/or with known values ofvarious structures, the identity of the target structure may beidentified.

Once the target anatomical structure has been identified, a treatmentdevice such as bipolar forceps 10 may operate as a conventional bipolarvessel sealer. The energy delivery configuration of generator 20 may beadjusted in accordance with the identified anatomical structure beingtreated. The closure pressure of the opposing jaw members 110, 120 mayalso be adjusted in view of the anatomical structure being sealed.

The electrical current produced by the processing unit 25 may varydepending on the type of tissue and/or the anatomical structure (e.g.,duct, vasculature, vessel, organ, etc.) being identified. Processingunit 25 is configured to produce AC and/or DC current. Processing unit25 may be configured to generate an electrical signal having a frequencyranging from RF (100 kHz) upwards of microwaves (low MHz to GHz).Depending on the application, processing unit 25 may produce a signal ofconstant frequency, a cascaded pulse interrogation signal (e.g., acosign shaped pulse), or may instead perform a frequency sweep oramplitude sweep.

More than one sensor assembly 50 may be connected to the processing unit25. In this manner, the one or more sensor assemblies 50 of a particularinstrument may include different electrode configurations depending onthe anatomical structure and/or signal frequency being tested.Processing unit 25 may include any suitable methods of increasing theaccuracy and consistency of the signature tissue property measurements,e.g., filters and multi-frequency readings.

Processing unit 25 may operate in a number of modes. Processing unit 25may be configured to alert a user when sensor assembly 50 has contacteda specific anatomical structure (e.g., vasculature, duct, vessel,tissue, organ, etc.). In this manner, a user would set processing unit25 to scan for a particular signature property (e.g., electricalconductivity, thermal conductivity, capacitance, impedance, etc.).Processing unit 25 produces an electrical signal configured to bestidentify the signature tissue property. The electrical signal producedby processing unit 25 may be manually determined by the user or mayinstead be automatically determined by processing unit 25. Theelectrical signal produced may include a specific frequency or range offrequencies and/or may include a specific signal configuration. Sensorassembly 50 may be placed in contact over a portion of tissue or inclose proximity thereto. As sensor assembly 50 contacts or approachestissue of the target type, as determined by processing unit 25,processing unit 25 may alert the user. The alert may be audio and/orvisual. With this purpose in mind, an audio and/or visual indicator 22(FIGS. 1A and 1B) may be included in/on the generator 20 and/or theinstrument utilized in the procedure (not explicitly shown).

One example procedure where identification of target and surroundingcritical anatomical structures is important is laparoscopiccholecystectomies to remove a gallbladder from a patient. By way ofexample, FIGS. 3, 4A, 4B, and 6 show a general rendering of thegallbladder region of a patient to illustrate the presenting ofelectrosurgical and/or non-electrosurgical instruments relative to suchregion. In this procedure, a surgeon removes the gallbladder from thecystic duct and occludes the cystic duct to prevent bile leaking fromthe common bile duct. Therefore, the cystic duct must be correctlyidentified by the surgeon so that the cystic duct, rather than thecommon bile duct, receives treatment (e.g., RF energy, microwave energy,excision, resection, occlusion, ligating, etc.). Other criticalstructures, such as the cystic artery and hepatic artery are in closeproximity to the cystic duct and common bile duct and must be correctlyidentified by the surgeon so as to avoid treating or otherwiseinadvertently injuring such critical structures.

Another procedure where identification of target and surroundinganatomical structures is important is an ureterostomy. By way ofexample, FIG. 5 shows a general rendering of a bladder and kidney regionof a patient to illustrate the presenting of electrosurgical and/ornon-electrosurgical instruments relative thereto. In this procedure, thesurgeon detaches one or both ureters disposed between the kidneys andthe bladder. Therefore, the ureter(s) must be correctly identified bythe surgeon so that the ureter(s), rather than the bladder or kidneys,receives treatment. During other procedures, such as gynecological andcolorectal procedures, nearby critical structures such as the ureter(s)are to be avoided and, thus, correct identification thereof is importantso that the surgeon is able to avoid treatment of the ureter(s) and/orincidental contact between a surgical device and the ureter(s).

Turning now to FIGS. 3-6, various embodiments of electrosurgical andnon-electrosurgical instruments that are utilized in conjunction withone or more sensor assemblies 50 are shown and include, withoutlimitation, monopolar instrument 2, bipolar forceps 10, grasper 200,dissectors/probes 200′, 300, 300′, and catheter 300″. Referringinitially to FIG. 3, electrodes 112, 122 of bipolar forceps 10 areembodied as the active and receiving electrodes 50 a, 50 b of sensorassembly 50, respectively. Forceps 10 is shown with a target anatomicalstructure (e.g., cystic duct) disposed between jaw members 110, 120while in an open position. In this scenario, while grasping (or prior tograsping) the target anatomical structure with forceps 10, theprocessing unit 25 transmits the electrical signal from the transmittingelectrode 112, 50 a through the target anatomical structure and/or thecontents (e.g., bile) of the target anatomical structure (referencedgenerally as “B”) to the receiving electrode 122, 50 b to elicit aresponse from the target structure. Once the target anatomical structureis identified by the processing unit 25, by methods describedhereinabove, the user is alerted by the audio/visual indicator 22 as tothe identity of the target structure. If the identity of the targetanatomical structure is revealed to be the target structure designatedfor treatment, the user may either grasp the target structure betweenjaw members 110, 120, if such structure was not already grasped betweenjaw members 110, 120, and selectively apply electrosurgical energy fromthe generator 20 to the structure. If the identity of the targetstructure is revealed to be a critical structure not in need oftreatment and/or to be avoided to prevent unnecessary treatment to thepatient, the user may release the target structure from the grasp of jawmember 110, 120, if necessary, and move forceps 10 away from suchstructure to avoid complications.

Referring now to FIG. 4A, a plurality of surgical instruments includingforceps 10, a grasper 200, and a dissector or probe 200′ are shown andmay be used during a procedure in conjunction with a sensor assembly 50to elicit a response from a target anatomical structure such that theprocessing unit 25 may calculate a signature property measurement ofsuch target structure. More specifically, grasper 200 is shown in anopen position with a target anatomical structure (e.g., gallbladder)disposed between the transmitting and receiving electrodes 50 a, 50 b.Dissector/probe 200′ is shown positioned about a different anatomicalstructure (e.g., cystic artery) than grasper 200. In this scenario,prior to grasping a target anatomical structure with forceps 10, thegrasper 200 and/or the dissector/probe 200′ may be utilized inconjunction with processing device 25 to identify respective anatomicalstructures, using methods described hereinabove. For example,transmitting electrode 50 a disposed on grasper 200 may be utilized totransmit an electrical signal to receiving electrode 50 b (e.g.,disposed on grasper 200, dissector/probe 200′, or any other suitableinstrument) via the conductive tissue of the gallbladder and/or theconductive content within the gallbladder (e.g., bile), referencedgenerally as “B”, to elicit a measurable response from the gallbladder.In the illustrated embodiment, once the grasper 200 retracts thegallbladder and the dissector/probe 200′ correctly identifies the cysticartery, forceps 10 may be subsequently navigated by the user away fromthe cystic artery and toward the cystic duct for subsequent grasping andapplying of electrosurgical energy thereto. As discussed hereinabove,the identity of these anatomical structures may be based on thedifferences between the calculated signature properties thereof (e.g.,cystic duct vs. cystic artery) and/or based on the comparison betweenthe calculated signature properties thereof and known signature propertyvalues of various anatomical structures, as determined by the processingunit 25.

Referring now to FIG. 4B, a plurality of surgical instruments includingforceps 10, grasper 200, and dissector/probe 200′ are shown and may beused during a procedure in conjunction with a sensor assembly 50 toelicit a response from a target anatomical structure such that theprocessing unit 25 may calculate a signature property measurement ofsuch target structure. More specifically, forceps 10 is shown graspingthe gallbladder between jaw members 110, 120, grasper 200 is shown in anopen position with a target anatomical structure (e.g., cystic duct)disposed between the transmitting and receiving electrodes 50 a, 50 b,and dissector/probe 200′ is shown positioned about a differentanatomical structure (e.g., common bile duct) than grasper 200 andforceps 10. In this scenario, any one or combination of forceps 10,grasper 200, and dissector/probe 200′ may be utilized to source ortransmit the electrical signal generated by processing unit 25 via atransmitting electrode 50 a to a receiving electrode 50 b disposed onany one or more of the above listed instruments utilizing anatomicalstructures and/or the contents (e.g., bile “B”, urine “U”, etc,) of suchanatomical structures to complete a circuit therebetween. That is, thecontent (e.g., bile “B”, urine “U”, etc.) within the various anatomicalstructures (e.g., gallbladder, common bile duct, cystic duct, etc.) mayoperate to complete a circuit between any one or more transmittingelectrodes 50 a and any one or more receiving electrodes 50 b of theillustrated instruments (e.g., forceps 10, grasper 200, dissector/probe200′).

The number and combination of instruments used to perform each of themethods of the various embodiments described herein are illustrativeonly in that any number of instruments and any combination ofinstruments may be incorporated to perform the methods described withrespect to the illustrated embodiments of FIGS. 3, 4A, 4B, 5, and 6.

In some embodiments, forceps 10 and/or grasper 200 may include apressure sensor (not explicitly shown) configured to sense graspingpressure applied to a target anatomical structure (e.g., via jaw members110, 120). For example, the pressure sensor may be embodied as atwo-dimensional pressure sensor pad disposed on the grasping surface(s)of grasper 200 and/or forceps 10. In this way, when a target anatomicalstructure is grasped by grasper 200 or forceps 10, the grasping pressureapplied to the target structure may be sensed and optimized foreliciting a response therefrom using transmission of the electricalsignal from processing unit 25 therethrough. More specifically, if toolittle pressure is applied to the target structure, the electricalsignal transmitted through the structure may be too weak to elicit aresponse. Likewise, if too much pressure is applied to the targetstructure (especially relevant when applying pressure to ducts orvessels), the target structure may be occluded, thereby not allowing forthe inclusion of fluid flow through the target structure whencalculating signature properties thereof. In one embodiment, thepressure applied to the target structure may be optimized by initiallyeliciting a response in the target structure while increasing theapplied pressure thereto until a step or a threshold change inconductivity is sensed. Once the step or threshold change inconductivity is sensed, pressure applied to the target structure may bedecreased to allow for fluid flow through the target structure, at whichtime a response is again elicited from the target structure, therebyproviding a relatively more reliable and repeatable measurement ofsignature properties of the target structure that includes the flow offluid therethrough. Controlling pressure also ensures that anatomicalstructures are not inadvertently crushed between the closing jaw members(e.g., jaw members 110, 120) of a vessel sealing type instrument (e.g.,forceps 10). With this purpose in mind, an initial sensing pressure maybe applied to the target structure followed by a tissue sealingpressure, with the vessel sealing type instrument configured to controleach of the initial sensing pressure and the sealing pressure.

The two-dimensional pressure sensor may also be used to identify tubularstructures within a jaw member(s) 110, 120. The identification of atubular structure (e.g. duct, artery, etc.) in combination with thesensed electrical properties, thermal properties, optical properties,etc. of the tissue may add additional information that better identifiesthe critical structure within jaw members 110, 120.

In certain embodiments, sensor assembly 50 may be disposed at the distalend of a suitable instrument (e.g., forceps 10) such that as sensorassembly 50 approaches a target anatomical structure, processing unit 20may first identify the target structure and subsequently alert the uservia audio/visual indicator 22 as to the identity of the anatomicalstructure being approached and/or sensed in the proximity of sensorassembly 50. This scenario is shown, by way of example, in FIG. 5. Inparticular, probe 300 is shown approaching a left ureter of a patientand probe 300′ is shown approaching a right ureter of a patient inproximity to catheter 300″ disposed within the right ureter, asdiscussed hereinabove. The distance between the sensor assembly 50 and atarget anatomical structure may be sensed by the sensor assembly 50 bytransmitting the electrical signal directionally or radially outwardfrom the transmitting electrode 50 a, as indicated by arrows “A” and“A′” in FIG. 5, such that the transmitted electrical signals willcontact anatomical structures in the proximity of sensor assembly 50 toelicit a response therefrom that is received by the receiving electrode50 b, as indicated by arrows “B” and “B′” in FIG. 5, and subsequentlyprocessed by the processing unit 25. In this manner, the processing unit25 may determine both the identity of the target anatomical structure,as discussed hereinabove, and the distance between the sensor assembly50 and the target anatomical structure. In this scenario, the user maybe alerted with increased conspicuousness or urgency as the sensorassembly 50 gets closer to the target anatomical structure. For example,the alert generated by audio/visual indicator 22 may vary audibly (e.g.,volume, frequency, timing, style, etc.) and/or visually (e.g.,frequency, brightness, color, style, etc.) depending on the proximity ofthe target anatomical structure to the sensor assembly 50. In thismanner, as the distance between sensor assembly 50 and a targetanatomical structure decreases, the alert generated by the audio/visualindicator 22 may be more conspicuous or more urgent relative to an alertcorresponding to a greater distance between sensor assembly 50 and thetarget anatomical structure to indicate to the user that the sensorelectrode 50 is approaching a critical anatomical structure that shouldbe avoided. In some embodiments, output from the generator 20 (e.g., RFenergy) to the instrument being utilized in the procedure (e.g.,monopolar instrument 2, bipolar forceps 10) may be set by the surgeon tobe modified or terminated based on the distance between the sensorassembly 50 and the target anatomical structure. In this instance,output from the generator 20 may be terminated or decreased if theinstrument gets too close to a critical anatomical structure (e.g.,hepatic artery, common bile duct, etc.) not intended to be treated orcontacted by an instrument. The visual output of the sensor assembly 50(e.g., electrical, thermal, optical, etc.) may be presented on a monitorincluded on the generator 20 or on another suitable display device inthe operating room (e.g., camera monitor).

Referring now to FIG. 6, forceps 10 is shown including transmittingelectrode 50 a and receiving electrode 50 b disposed on a distal portionof jaw members 110 and 120, respectively. In the illustrated embodiment,jaw members 110, 120 are disposed about a target anatomical structure(e.g., cystic artery) and in the open position. In this scenario, eitherprior to or while grasping the target structure between jaw members 110,120, electrodes 50 a, 50 b are utilized in conjunction with processingdevice 25 to identify the target structure, using methods describedhereinabove. For example, transmitting electrode 50 a disposed on jawmember 110 may be utilized to transmit an electrical signal to receivingelectrode 50 b disposed on jaw member 120 via the conductive tissue ofthe cystic artery to elicit a measurable response from the cysticartery. Depending on the identity of the target structure, forceps 10may grasp the target structure, if not already grasped, and selectivelyapply electrosurgical energy thereto or, alternatively, be moved awayfrom the identified structure to avoid injury thereto. For example, theforceps 10 may be moved away from the cystic artery and toward thegallbladder to elicit a measureable response therefrom (as illustratedin FIG. 4B) utilizing the conductive tissue of the gallbladder and/orthe conductive content within the gallbladder (e.g., bile), referencedgenerally as “B”.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. A method for determining proximity of a surgicaldevice relative to an anatomical structure, the method comprising thesteps of: placing at least one surgical device having a sensor assemblydisposed thereon relative to a target anatomical structure, the at leastone surgical device including a pair of jaw members movable relative toeach other; transmitting at least one first electrical signal from thesensor assembly via one of the jaw members through a content of thetarget anatomical structure to the other jaw member to elicit ameasurable response from the content of the target anatomical structure;calculating one or more signature properties of the target anatomicalstructure based on the measureable response; comparing values of atleast one first measured signature property to at least one secondmeasured signature property; and determining the identity of the targetanatomical structure and proximity of the at least one surgical devicerelative to the target anatomical structure based on the comparisonbetween the at least one first measured signature property and the atleast one second measured signature property.
 2. A method according toclaim 1, further comprising the step of modifying an application ofelectrosurgical energy to the target anatomical structure based on thedetermining step.
 3. A method according to claim 1, wherein the at leastone electrical signal of the transmitting step is transmitted from atransmitting electrode of the sensor assembly through the anatomicalstructure to a receiving electrode of the sensor assembly.
 4. A methodaccording to claim 1, wherein the measurable response is based on atleast one of tissue of the target anatomical structure and at least onefluid within the target anatomical structure.
 5. A method according toclaim 4, wherein the at least one fluid is selected from the groupconsisting of blood, bile, urine, feces, saliva, water, mucus, anddigestive enzymes.
 6. A method according to claim 1, further comprisingthe step of delivering a contrast agent through the target anatomicalstructure to modify the measurable response.
 7. A method according toclaim 1, wherein the at least one second measured signature property isat least one known signature property of the target anatomicalstructure.
 8. A method according to claim 1, wherein the placing stepfurther comprises the step of grasping the target anatomical structureprior to the transmitting step.